JP3471014B2 - Battery charging method and device - Google Patents

Abstract

A battery charging system is provided, comprising a rechargeable battery (40) including at least one rechargeable battery cell, a pair of battery terminals and information means (41) for containing information about the battery in the form of an information code, a charging apparatus (42) for charging the rechargeable battery (40), the charging apparatus including a pair of charger terminals, means for releasably interconnecting the battery and the charging apparatus so that the battery terminals are in electrical conductive contact with the charger terminals, and information receiving means for electronically reading or sensing the information code of the information means of the battery, said charging apparatus (42) further comprising control means (43) for controlling the charging process based on the information code received by the information receiving means of the charger. The invention further relates to a battery for use in said rechargeable battery system.

Description

DETAILED DESCRIPTION When charging a rechargeable battery such as a NiCd battery, a voltage higher than the terminal voltage of the battery is applied to the terminals of the battery, resulting in a current flowing through the battery. This current initiates a chemical process that causes energy to be stored in the cell.

When the battery reaches full charge, the chemical process is stopped and the energy applied is instead converted to heat. Since the battery is manufactured as a closed container, the pressure inside the battery increases, which causes chemical destruction. This means that the capacity of the battery is reduced, and that capacity eventually drops significantly after many such chargings. Therefore, in order to use the battery in the most appropriate manner, it is important to ensure that the battery is not only fully charged, but that the charging is interrupted before the heat generation becomes too great. . Therefore, it is desirable to control the charging process to achieve near-optimal charging and / or stop charging at the proper time. This precise control of the charging process is especially important when it is desired to charge the battery as quickly as possible.

In a typical charging process, the voltage across the battery terminals rises uniformly as the battery is charged. As the battery approaches full charge, the voltage rises more rapidly, peaking at full charge. The battery voltage then drops again due to the increase in temperature. This is because the temperature coefficient of voltage is a negative value. Therefore, the charging current generally drops to a minimum when fully charged and then rises.

The present invention is a method of charging a rechargeable battery having a pair of terminals; connecting the terminals of the battery to a power source and charging the battery with a value and / or course of at least one characteristic parameter of the charging process. Stored reference to investigate the value and / or course of said at least one charging parameter to indicate the ideal or desired charging process for various types of batteries and / or different battery conditions. Compare with the corresponding value and / or course of the parameter,
Selecting at least one of the stored parameters of the reference parameters based on the comparison and then controlling at least a portion of the process of charging the battery based on the one or more of the selected set reference parameters. It provides a charging method.

According to a first aspect of the invention, the first characteristic parameter is controlled such that at least part of the process of charging obtains a predetermined desired course of the second parameter of said characteristic parameters, and The first parameter is a charging current and the second parameter is a charging voltage.

When a battery is charged for the first time, or if the battery is stored without being charged for a long period of time, such battery (hereinafter referred to as "virgin battery") cannot immediately accept the normal full charge current. . Therefore, the process of charging such virgin batteries cannot be controlled in the same manner as other batteries of the same type and state of charge but not virgin batteries. Therefore, to know if the battery is a virgin battery,
Although it is advantageous to test the battery to be charged before it is actually charged, this test may be carried out, for example, for an individual "protection" program (" nursing "programme) is required. Also, non-virgin batteries show some sort of abnormality.

Therefore, according to another aspect, the invention is a method of charging a rechargeable battery having a pair of terminals; connecting an electronic terminal to a power source and a first test charge stream to the battery terminal,
The battery is first subjected to a test charge by sending a short first period of time, followed by a survey or measurement of at least one test parameter during or at least a portion of the test charge process, followed by a short second Conducting a test discharge of the battery for a period of time and investigating or measuring at least one test discharge parameter during or at least at a part of the test discharge process, the test charge process and / or the test discharge process being investigated. Or selecting or determining a course or value of at least one charging parameter based on the measurement and then substantially following the selected course or value for said at least one charging parameter.
A method comprising at least partially charging a battery is provided.

Test charging of the battery can be done in any suitable manner. For example, a pre-fixed test charge voltage may be applied to the battery terminals for a predetermined period. Alternatively, the test charging voltage may be increased gradually or stepwise in a predetermined manner. In both cases, the charging current,
The temperature of the battery and / or the internal pressure of the battery is investigated or measured continuously or at one or more selected points in the process of battery and / or discharge.

Another possible method is to control the test charge voltage to maintain the charge current at a predetermined level, or to increase the test charge current in a predetermined manner in a gradual or stepwise manner. is there. In the latter case, the charging voltage, the temperature of the battery and / or the internal pressure of the battery are investigated or measured.

It is advantageous to repeat the process of test charging and test discharging one or more times. By repeating the process in this way, a controlled course of test parameters (charging voltage or charging current) can be selected differently for the next test charging process.

A relatively low test charging current, eg about 0.2 C / h (CmA × h is the capacity of the battery), so that the temperature and / or internal pressure of the battery is not at a value that has a harmful effect on the battery.
It is preferable to send it to the battery.

Each test charging period is preferably shorter than the period of the next actual charging. For example, each test charge is performed for several seconds, for example, 1 second or 2 seconds.

The protection program selected based on the above tests includes the full battery charging process followed by a discharging process and a new charging process. If the selected protection program is discontinued before the battery is fully charged, the battery will be further charged, and the further charging method will be at least part of the process of charging the battery. The value and / or course of at least one characteristic parameter is investigated and the value and / or course of said at least one charging parameter is used for ideal or desired charging for different types of batteries and / or different battery conditions. Comparing with corresponding values and / or courses of stored reference parameters indicative of the process, selecting one of said stored sets of reference parameters based on said comparison, and then selecting one of said selected sets above. Control at least a portion of the battery charging process based on one or more reference parameters. It is a method that consists of.

A small or large number of empirically determined parameters (eg a draft in which the value of the reference parameter is plotted against the elapsed time since the start of the charging process) is
For example, it can be stored by electronic storage means such as a memory. If it is desired to charge a rechargeable battery quickly without being substantially degraded, the ideal or desired charging process will depend primarily on the state of charge of the battery prior to initiating the charging process. Therefore,
The stored course of reference parameters indicates the ideal or desired charging process for batteries with different starting states of charging. If the state of charge of the battery to be recharged is known or measurable, a reference course with a starting state of charge that is also close to the actual state of charge of the battery to be recharged is selected and the process of charging that battery is , It is possible to control the course of said at least one parameter to approach a selected reference course, so that the battery is not exposed to excessively high voltage or charging current or to excessive heating at any time. can do.

In principle, the state of charge of the battery to be recharged is determined in a particular measurement step, and then the course of the corresponding reference parameter applied to the starting state of the same or similar charge, e.g. Can be selected by giving relevant information to. However, in the preferred embodiment, the associated reference course is automatically selected by the electronic control circuitry.

The charging parameters include, for example, the potential difference between the battery terminals, the charging current supplied to the battery, the temperature of the battery cell, the rate of change of such parameters, and combinations of such parameters and / or rates of change.

It should be understood that the charging process can be controlled in any suitable manner that allows the course of charging parameters to approach the selected reference parameter course. However, in the preferred embodiment, the charging process is controlled by controlling the voltage applied across the terminals of the battery. The voltage is then maintained at substantially the same maximum value in the next large part of the charging process as the charging current delivered to the battery is relatively low at the beginning of the charging process but preferably that charging current accelerates the charging process. So that it is controlled.

As mentioned above, the choice of the reference parameter depends on the state of charge of the battery. Such state of charge can be determined by applying a short voltage to the battery before starting the charging process, as it measures one or more charging parameters. If the battery is fully charged, the charging process will not start. If the battery is partially charged, such information can be used to select appropriate reference parameters for the charging process.

The control of the charging process consists of determining the remaining charging period when the value of at least one characteristic parameter fulfills one or more specific predetermined conditions, and then such remaining period. The charging process is stopped when In an embodiment of the method according to the invention, the remaining charging period is determined when the characteristic parameters such as charging voltage, charging current, battery temperature or battery internal pressure reach a predetermined value.

Near the end of the charging process, the internal resistance of the battery cell rises, which tends to increase the charging voltage when the charging current must be maintained at a predetermined, relatively high value. If the voltage is too high, it causes a harmful temperature rise in the battery cell. Therefore, it is preferable to limit the voltage applied between the terminals of the battery to a predetermined maximum value, and the charging process begins when the voltage reaches the maximum value and the predetermined remaining time has elapsed. Sometimes canceled. This means that it is preferable to keep the charging voltage at its maximum value for the rest of the predetermined period mentioned above, and as the internal resistance of the battery cell rises, the charging current usually stays during this period. Gradually decreasing, this period is preferably chosen such that the battery is substantially fully charged when the period has elapsed. This predetermined remaining time period is preferably associated with a selected reference course, which means that each reference parameter course provides information on the charging period as well as information on the maximum charging voltage to be applied to the battery. It is meant to have information on how long such a maximum voltage must be maintained until the end.

As mentioned above, the course of the reference parameter that is compared to the course of the actual parameter is a curve or graph, and the comparison process uses a design recognition circuit (design recognition circuit).
It can be carried out by a design recognition method based on recognition circuitry). However, in a preferred embodiment of the invention,
The charging parameter is continuously measured during charging in short time intervals, the measured parameter value is compared with the corresponding reference value of the course of the reference parameter, and then the course of the relevant reference parameter is measured and the reference value above. Selected based on a comparison of This comparison process is continued during the charging process and when the successive comparison processes indicate that the course of the initially selected reference parameter is not the closest course of the actual charging process, the control circuit or The controller shifts from one reference parameter course to another.

When comparing the charging parameter value with the reference value, it is advantageous to compare the rate of change of the parameter value as a function of the charging elapsed time with a similar reference value. For example, the rate of change of charging voltage as a function of elapsed charge time can be compared to a corresponding reference value. Since the internal resistance or potential difference of the battery can be detected, the charging current can be cut off for a short time immediately before measuring the potential difference between the terminals of the battery.

The parameter value is measured, and then the rate of change of the parameter value is determined in a uniform first time interval, each measurement of the rate of change being based on the parameter value measured in the second time interval, The time interval of is several times as long as the first time interval. Parameter values are measured fairly often, which means that the first time interval is relatively short,
For example, it means about 10 seconds. However, it is preferred that the rate of change is based on measurements at several times larger time intervals, eg 90 seconds.

The rate of change measurement can start at the beginning of the charging process. However, if it is clear that the highest identifiable rate of change is found after the measured rate of change of the characteristic parameter exceeds a predetermined value, then the measured rate of change of the characteristic parameter is predetermined. It is advantageous to postpone until the value is exceeded.

In particular embodiments, the number of reference values is limited, and the new stop time of the charging process is determined only when the associated parameter or parameters assume a single reference value. The result is a simpler method by which the optimum stopping point can still be determined normally and with sufficient accuracy.

As mentioned above, if the parameter to be measured is the voltage across the connection terminals of the battery, a more accurate measurement is obtained when the charging current to the battery is briefly disconnected before measuring the voltage. The reason is that the battery has an internal resistance in series,
The charging current then causes a voltage drop across the resistor which should not be included in the voltage measurement.

Especially when performing a fast charging method using a high charging current,
It is advantageous to gradually reduce the charging current as the stop time approaches. Because it is easier to find the optimal stopping point. Thus, charging is carried out, for example, at a constant high charging current (e.g. about 4 CmA when the capacity of the battery is C mA x time) until one of the measured parameters reaches the determined level, after which the charging current is Can be gradually reduced.

A suitable method for obtaining the desired charging current is to use a constant voltage voltage source that is pulse width modulated to provide the desired charging current.

Advantageously, the procedure for determining the possible stop points for the charging process does not start until the charging process approaches the stopping point. Therefore, a simpler method, such as a simple measurement of current or voltage, can be used to determine when a more accurate procedure should be initiated.

In a particular embodiment, the accuracy of the measured values is improved by the fact that each measured value of the characteristic parameter for each of the above time points is an average value of a plurality of intermediate measured values. Therefore, these measurements are not sensitive to transients, for example. Of course, the same effect can be obtained by integrating the parameter over the time elapsed since the last measurement.

As an additional safeguard, some stopping criteria used in the prior art can be adopted. For example, the maximum charging period can be fixed. In that case, no matter how late the stopping criterion is, the charging is stopped at this point no matter how late. It is also possible to place limits on one or more measured parameters and stop charging if one of these parameters exceeds or drops below a certain value. Furthermore, the charging process is aborted if the at least one value or course being investigated deviates significantly from any of the corresponding courses or values of the stored reference parameters.

It is appropriate to maintain the state of charge of the battery by pulsating current after stopping charging. By doing this,
Batteries are guaranteed to be fully charged at all times without having to remove them from the charger for a long period of time after stopping charging.

The stored reference parameter courses are not only those that show an ideal or desirable charging process for one and the same type of battery, but also multiple reference parameter courses for two or more different types of batteries. Contains. In such a case, the first step in the process is to determine the type of battery to be charged and select the course of reference parameters associated with that type of battery. The process can then proceed as described above.

The invention also relates to a connecting means for connecting the battery to a power source; the value of at least one characteristic parameter of the charging process and / or at least part of the process of charging the battery.
Or means for investigating the course; storage means for storing a plurality of values of reference parameters and / or courses indicative of an ideal or desired charging process for different types of batteries and / or different battery conditions; at least one charging parameter as described above Value and / or course of
Means for selecting one of said stored sets of reference parameters based on said comparison, relative to a stored value and / or course of reference parameters; and one or more references of said selected set. Means for controlling at least a portion of the process of charging the battery based on the parameters;

The operation of such a device can be controlled by, for example, a microprocessor or other electronic control device,
These devices also include a memory that stores the course or value of the reference parameter.

According to yet another aspect, the invention provides a rechargeable battery having a pair of battery terminals and an information means containing information about the battery; and a pair of charger terminals, a battery terminal and a charger terminal. Means for removably interconnecting the battery and the charging device in electrically conductive contact,
And a charging device having information receiving means for receiving information from the information means of the battery; as a result, there is provided a battery system capable of controlling charging of the battery based on the information. The electronic system may comprise control means for controlling the charging process based on the information received by the information receiving means.

The information means of the battery is a little elaborate. The simplest form of information means comprises, for example, an indicator which is removed, deactivated and / or destroyed when the battery is first charged. The presence of such an indicator informs the control means that the battery should be charged according to the appropriate "protection program" for the virgin battery of that battery type. Alternatively or additionally, the information means may have an information code that can be read or detected by the information receiving means of the charger. Such an information code can be read or detected by mechanical, optical, electromagnetic and / or electronic reading or detecting means, and the code can include, for example, battery type, capacity, maximum Contains information about charging voltage, maximum charging current, maximum temperature, maximum internal pressure and / or other characteristics. Furthermore, the information means may also or additionally include a temperature sensor for detecting the temperature of the battery.

In a preferred embodiment of the battery system of the present invention, when the temperature detected by the temperature sensor is low, the charging current and / or the charging voltage rises first.

The present invention also relates to a rechargeable battery used in the above battery system, wherein the battery contains battery information in a form that can be detected or read by a pair of battery terminals and an appropriate information receiving means of a corresponding battery charger. I have information means.

As mentioned above, the information means are fairly simple. Alternatively, the information means may include an electronic memory that stores battery information. This battery information contains information about one or more previous charging and discharging processes and / or information about the current state and conditions of the battery and its individual battery cells. The battery information means thus informs the control means in detail about the battery conditions, which can then control the charging process on the basis of such information. Such charging can be controlled by any of the above methods or by conventional charging methods. The battery information includes, for example, battery type, battery capacity, battery outer specifications, battery charge status, various battery tank conditions, last charging process, last discharging process,
Time elapsed since the last charging and / or discharging process, charging parameter algorithm and / or
Or contains information about the internal pressure of the battery.

In order to check the internal pressure and / or temperature of the battery, the information means may comprise a pressure and / or temperature sensor provided in the battery. These sensors are or can be connected to the control means such that information about pressure and / or temperature is communicated to the control means.

The control means is preferably arranged to control the charging of the individual cells of the battery in response to the information received from the information means, so that the cells of the battery are guaranteed to be charged substantially uniformly.

It should also be understood that the battery of the present invention comprises an electronic display which displays information from the memory in a direct readable form. Further, the battery of the present invention is considered to have a control means. This means that the charging device is not included or is included in the battery device. In such cases, the battery must be directly connected to a suitable power source.

Normally, a battery is composed of several battery cells, and the information means measures the voltage of each battery cell in order to obtain information about the individual battery cells, for example, the voltage and / or temperature information of each battery cell. The information means may store the measured value and the measured value of the battery tank.

In connection with the above charging method, it is a prerequisite that a course or set of reference parameters is known and available for the type of battery in question. The present invention provides a method of providing such a course or set of reference parameters. Therefore, the present invention is based on the capacity C
A method of determining a process for charging a rechargeable battery having: a maximum value for at least one charging parameter, and then the charging process not exceeding the determined maximum value or values. To provide a method of controlling.

It is usually desirable to fully charge the battery within the shortest possible charging period. However, the charge rate is limited by the chemical reactions that occur in the battery tank. When the charging current is relatively low, the temperature of the battery increases without increasing the temperature of the battery by increasing the charging voltage, and the temperature of the battery decreases slightly but even decreases when the charging current increases. However, when the charging current reaches its maximum value determined by the chemical reaction, the higher charging voltage causes a drastic rise in the battery temperature and internal pressure, which is harmful to the battery. According to the invention, maximum values of temperature, temperature difference, internal pressure, charging voltage and / or terminal voltage are determined for a battery and / or its cell. The charging process must then be controlled so that no single or multiple maximum values are exceeded during the charging process.

For example, the maximum and / or difference in the temperature of the battery / battery and / or the internal pressure of the battery / battery may be such that a relatively low charging current is delivered to the battery for a certain period of time, for example about 1 hour or 10 or 15 hours. Temperature and / or temperature difference and / or pressure obtained when The charging voltage is also controlled so that the charging current remains substantially constant, at least during the latter part of the charging process. The charging current sent to the battery is, for example, 0.05
-0.3 C / h, 0.1-0.3 C / h, preferably 0.2-0.25 C / h [C / h is the so-called C-rate]. This means that when the capacity of the battery to be charged is CmA · h, the charging current is 0.05-0.3CmA, 0.1CmA and preferably 0.2-0.25CmA. Such a charging current is relatively low, so it takes 3.3 to fully charge the battery.
Charging time of ~ 10 hours is required.

To make the charging time even shorter, it is necessary to use a higher charging current for a large part of the charging period. The maximum value of the charging voltage and / or the terminal voltage is determined as the maximum value obtained when a relatively high charging current is delivered to the battery for a certain period of time. Such a relatively high charging current is, for example, 0.75 to 1.5 C / h, preferably about 1 C / h. When using such a charging current, the charging time required to fully charge the battery is 0.67 to 1.34 hours.

The charging current may be delivered to the battery for a period sufficient to partially charge the battery, but it is preferred to continue delivering charging current to the battery until the battery is substantially fully charged.

When determining one or more of the above maximum parameters, the battery is preferably at least partially charged at a slow rate and then discharged at least once before further charging. Also, its relatively low charging current should be delivered to the battery for a long period of time such that at least one of the aforementioned charging parameters, such as the temperature of the battery or battery cell, rises and no other essential parameter changes should be detected. Is more preferable.

The actual value of the battery capacity is often different from the capacity stated by the battery manufacturer. Therefore, one object of the present invention is to provide a method for determining the actual value of the capacity of a battery. This method involves charging or summing the battery at said relatively slow rate and then calculating or summing the sum of the initial charging power delivered to the battery during charging until the battery is substantially fully charged. It is a method consisting of determining the capacity of the battery. The time when the battery is substantially fully charged is determined as the time when no further increase in the parameter value was detected during the predetermined period. The parameter values are, for example, the temperature of the battery and / or its cell and / or the terminal voltage.

When determining the maximum value of the charging voltage or terminal voltage, it is preferable to charge the battery with a charging current that is substantially equal to the C-rate based on the measured actual value of the capacity of the battery. In addition, the maximum voltage difference between the terminals of the battery or battery case measured when the temperature of the battery or battery case rises to the maximum temperature difference measured during charging with the relatively low charging current described above. It is preferable to determine the value. It is also preferred that the battery be substantially discharged prior to initiating the charging process in order to measure charging parameters.

If the battery is a virgin battery (which means that the battery is being charged for the first time or a long time has passed since the last charge), the battery will definitely "start up" (this is It means that the chemical reaction in the battery tank is normal). This can be achieved with the protection program described above. In this way, the battery is fairly slowly at least partially charged and then discharged at least once before determining the maximum value of said at least one maximum parameter.

The set of maximum values obtained by the method described above is the reference value used in the charging method described above. Other reference values or parameters can be obtained by controlling other charging parameters so as not to exceed the determined maximum charging parameter.

The set of maximum values and / or parameters obtainable as described above can be used for a controlled charging method. The battery is then charged with a substantially constant charging current as part of the charging process,
The substantially constant charging current is preferably several times the C-rate based on the determined or measured capacitance value. For example, the maximum value or parameter may be voltage. In that case, the voltage across the terminals of the battery or battery cell is investigated, and when the predetermined maximum voltage across the battery or battery cell is reached at time Tmax, the charging process is the rest of the charging process. The inside is controlled to maintain the voltage of the battery or battery cell substantially constant. If a battery has at least two battery compartments, investigate the various parameters or voltages of that cell and, for the remainder of the charging process, the voltage of the compartment where the voltage first reaches the maximum battery compartment terminal voltage. Controlled based on. It should be understood that the charging process can be controlled based on other charging parameters such as the temperature of the battery or its individual cells.

Also, when the rest of the charging process is stopped,
The determination is preferably made by examining the charging current, and the charging process is stopped when it is detected that the charging current does not drop further during the predetermined period. Or the charging process is stopped at Tstop,
The remaining charging period, Tstop-Tmax, is the time point Tm when the battery or battery cell reaches a predetermined maximum voltage.
Generally determined by ax. Remaining charging period or Tstop
-Tmax may be determined based on a comparison of the course of the voltage across the battery or battery cell with the stored course of the reference voltage, or the remaining charging period may be determined by the value of Tmax.

In a preferred embodiment of the invention, the stop time Tstop and the remaining charging period are the time Tmax at which the maximum voltage is reached,
It is determined based on a comparison of the stored time reference value and the corresponding remaining charging period.

For discharging when a battery is used for operation, the present invention is a method of controlling the discharge process of a rechargeable battery having at least two battery cells; examining the voltage of each battery cell of the battery, A method is then provided which comprises discontinuing the discharge process when the voltage of at least one battery cell drops to a predetermined threshold voltage.

  The present invention will be further described with reference to the following drawings.

FIG. 1 is a graph or curve showing voltage as a function of time for a NiCd cell charged with a constant charging current.

  FIG. 2 is a partially enlarged view of the curve of FIG.

FIG. 3 is a graph showing the course of various charging parameters of a controlled process of charging a NiCd battery.

FIG. 4 is a graph showing the battery voltage of a NiCd battery as a function of charging time for six different starting states of charging.

  FIG. 5 is a block diagram of the device of the present invention.

  FIG. 6 shows a circuit diagram of an embodiment of the device shown in FIG.

FIG. 7 is a graph showing a battery having some kind of abnormality corresponding to the graph shown in FIG.

8 and 9 are diagrams showing the charging curves at the beginning of the charging process for a virgin battery and for a fully charged battery, respectively.

Figures 10 and 11 show the discharge curve for a virgin cell and the discharge curve for a fully charged cell, respectively.

FIG. 12, shows the charge and temperature curves of a battery charged with a constant low charging current.

Figures 13, 14 and 15 show charge voltage and temperature curves, respectively, for the same cell shown in Figure 12 charged with different values of substantially constant charge current.

FIG. 16 shows a charging voltage curve and a temperature curve of a battery which was subjected to test charging at a constant low charging current within a range of 0.1 C / h.

FIG. 17 shows a charging voltage curve and a temperature curve of a battery which was subjected to test charging at a constant charging current within the range of 1 C / h.

18, 19 and 20 show the charging voltage curve, the temperature curve and the charging voltage curve of a NiCd battery charged with different values of charging current. The charging process is controlled by the preferred embodiment of the present invention.

FIG. 21 shows the charge voltage curve, temperature curve and charge curve of a Nickel Metal Hydride battery initially charged with a high charge current.

  FIG. 22 is a block diagram of the battery of the present invention.

FIG. 23 shows a discharge voltage curve of each battery cell of a NiCd battery having six battery cells and being discharged at a constant current.

FIG. 24 shows the controlled discharge process of the present invention performed on a NiCd battery having 6 battery cells.

FIG. 25 shows a charging voltage curve and a temperature curve of each battery cell of a NiCd battery having six battery cells and charged with a constant charging current.

26, 27 and 28 are block diagrams showing various embodiments of the battery system of the present invention.

Figure 1 shows a typical NiCd battery charging sequence. This curve shows the battery voltage as a function of time with a constant charging current. The general form of the curve is the same for all NiCd batteries, but the specific voltage and time values vary, for example, with the actual charging current and from battery to battery.

This curve can be divided into regions that represent the various stages of the charging process. FIG. 1 shows four regions labeled A, B, C and D, respectively.

Area A is the start area of the charging process. Once the charging process is initiated, the voltage will change somewhat depending on the state of charge of the battery before it begins charging. Therefore, the voltage in this region is rather indeterminate and, therefore, proper measurements are usually not made in this region.

B indicates the actual charging period, during which the charging current is converted by the chemical process and stored as energy in the battery. During this period, the battery voltage rises very slowly. In region C, the full state of charge is approaching and the voltage begins to rise more rapidly. At the end of period C, oxygen begins to develop in the battery cell of the battery, resulting in an increase in battery pressure and temperature. This means that in this case the voltage rises more slowly because of the negative temperature coefficient. The voltage of the battery reaches its maximum or peak value without further increase in the transition region between the C and D regions.

If the charging process continues in region D, the battery voltage will drop as electricity and energy are generally converted to heat. The increase in temperature and pressure results in the destruction of the battery, resulting in a decrease in battery capacity. Therefore, it is advantageous to stop the charging process at the beginning of period D.

The present invention provides for various charging parameter values within regions A, B and C, for example within region C, even though the voltage curve varies somewhat in response to the charging current used and the "charging history" of the battery. It is based on the finding by the tests that there is a close correlation between the slope of the voltage curve at a particular time and the time difference from that time to the optimal stop of the charging process.

When the information on the above correlation is stored in the electronic circuit, after measuring the slope of the voltage curve at a given time, how long the battery should continue to be charged and therefore the optimal stop time of the charging process is calculated. Or it is relatively easy to determine. Performing this calculation at any number of consecutive time points will yield a corresponding number of suggestions for the appropriate stop time points. FIG. 2 shows an example in which the measurement is performed three times. The remaining charging period ΔT1 is calculated at time T1, the remaining charging period ΔT2 is calculated at time T2, and the remaining charging period ΔT3 is calculated at time T3. In this FIG. 2, the three calculated stop points occur at exactly the same point. In practice, however, the calculated discontinuation times are usually slightly different in some of the proposed values obtained as discontinuation points. In the embodiments of the invention described herein, charge termination is determined when the first one of the calculated termination times is reached. Since the microprocessor is built into the device below, more sophisticated abort criteria can be envisioned. Therefore, for example, it is possible to attach importance to the last calculated stop point. For example, some of the first calculated values can be dropped if all subsequent calculated values are gathered around a particular value.

As mentioned above, FIGS. 1 and 2 show the voltage across the battery terminals as a function of time when a constant charging current is used. Plotting the charging current as a function of time with a constant charging voltage gives the corresponding typical curve, which shows a reproducible curve showing the above steps in the charging process, keeping the charging current and charging voltage constant. You can get it without doing it. It will be appreciated that these curves can be used in a manner similar to that described above.

For other types of cells, corresponding curves with different appearances are obtained. For some of these curves, the correlation between the actual measurement time and the optimal remaining charge time is not necessarily related to the slope of the curve at that time, but other parameters of the curve, such as the absolute voltage at the relevant time. Related to.

In an embodiment of the invention, the slope of the voltage curve is
It is measured every 1/10 second. For each measurement, a new suggested value is calculated for the remaining charging period and thus the point of suspension. The processor can then store this value along with other values or incorporate it in a more precise calculation of when to stop the charging process.

In another embodiment, a limited number of reference values for the slopes of the curves are pre-stored. At each measurement, the actual slope of the curve is compared with a reference value and the processor calculates a new stop time only if the slope exceeds one reference value. This saves processor computing time,
The results are often quite satisfactory.

As mentioned above, the curves of Figures 1 and 2 are provided using a constant charging current. However, another possible method is to interrupt the charging current for a short time after each voltage measurement. This method gives a perfectly matched curve,
The absolute voltage value is slightly lower because the curve does not include the voltage drop caused by the charging current through the internal resistance of the battery. This internal resistance generally increases at the end of the charging sequence, so a voltage measurement without its involvement is a more accurate measure of the state of the battery.

As mentioned above, a reproducible curve is obtained even if the charging current is not kept constant, for example during the entire charging operation. Thus, the principles of the present invention can be fully combined with a charging method in which charging is first done at a constant high current and then this current is reduced towards the end of the charging operation. By using a lower charging current in the final part of the charging process, the optimal stopping point can be more accurately determined without significantly shortening the total charging time. This method can be combined with making a very simple voltage measurement in the first part of the charging process. When the voltage reaches a predetermined value, the charging current is reduced and then the measurement of the slope of the curve is started in the same way as described above. Of course, it is also possible to reduce the charging current at one voltage value and then start measuring the slope of the curve at another voltage value.

FIG. 3 shows a typical charging curve obtained according to an embodiment of the method of the invention when charging a NiCd battery. This voltage curve shows the voltage of the battery as a function of time when the voltage applied to the battery is controlled according to the invention in order to obtain the optimum charging current curve and the optimum battery temperature curve. This battery voltage curve can be divided into regions similar to FIG. 1 showing the various stages of the charging process. FIG. 3 shows four regions labeled A, B, C and D respectively.

Area A is the start area of the charging process. In this region, the applied voltage is controlled so that the charging current delivered to the battery is relatively low.

Area B shows the actual charging period in which the charging current is converted in the battery and stored as energy. In this region, the applied voltage is controlled so that the charging current is maintained at substantially the same maximum value (determined by the battery type involved), and the voltage across the battery terminals rises very slowly. To do.

In region C, the battery approaches its fully charged state, and the voltage across the battery's terminals begins to rise more quickly until it reaches a predetermined maximum value Vmax in order to maintain the maximum charging current. The maximum value Vmax differs depending on the type of battery, and can be determined as described above, for example.

In region D, the applied voltage is controlled such that the measured voltage across the battery terminals is substantially maintained at the maximum limit value Vmax. In the regions C and D, the internal resistance of the battery tank increases, so when the battery voltage is constant as in the region D, the obtained charging current decreases. In region D, the voltage of the battery is maintained at a constant value, so the temperature rise that occurs is relatively low. Therefore, the destructive effect that occurs on the battery tank due to the charging current is minimized.

When Vmax is reached, the remaining charging period is determined before time Tmax. The charging process is stopped when the remaining charging period has elapsed, such as starting at Tmax.
The charging current delivered to the battery is controlled by a pulse width that modulates a constant voltage source.

The voltage curve shown in FIG. 3 shows the charging process of an almost unloaded NiCd battery. FIG. 4 shows six similar voltage curves V _{1 to} V ₆ showing different courses of charging the same battery with different starting charges. Curve V ₁ shows the charging process of the battery when it is almost fully charged, and curve V ₆ shows the charging process of the battery when it is almost completely discharged. FIG. 4 shows that the charging period required to obtain the maximum voltage Vmax increases when the state of charge at the start of charging the battery is low. It can also be seen from FIG. 4 that the "remaining charging period", which is the period from when Vmax is reached to when the charging process is stopped, increases when the state of charge at the start of charging the battery is low.

Information about the ideal or desired reference voltage curve for a battery of that type for a plurality of different charging conditions at the start of charging the battery can be stored in electronic memory. By comparing the course of the actual voltage curve, for example the slope of the curve, with a stored reference value, the associated reference voltage curve and its associated "remaining charging period" can be determined.

The slope of the voltage curve can be continuously measured, for example, every 1/10 second during the charging process. A new proposal for the "remaining charging period" is determined by comparison with the reference slope stored for each measurement. When the measured battery voltage reaches the stored maximum voltage Vmax, the "remaining charging period" determination is canceled and the last determined "remaining charging period" value is used.

In another embodiment of the method according to the invention, in which a charging curve of the type shown in FIGS. 3 and 4 is obtained, a limited number of reference values for the slope of the voltage curve are pre-stored. At each measurement, the actual slope of the curve is compared with its reference value and a new "remaining charge duration" value is determined only if the slope exceeds one of the reference values.

Curves corresponding to those shown in FIGS. 3 and 4 can be obtained for other types of cells. These curves may differ in appearance, and for some of them, the correlation between the time to reach the voltage Vmax and the optimal remaining charge period is not necessarily related to the slope of the voltage curve, It is related to other parameters of the curve such as absolute voltage at the time of The more parameters that are measured and stored, the more precise the determination can be made to determine the optimal remaining charge period.

In another embodiment of the method according to the invention, in which a charging curve of the type shown in FIGS. 3 and 4 is obtained, the slope of the voltage curve is measured when the maximum voltage value Vmax is reached and the voltage of the battery is measured at a fixed time. taking measurement. In this embodiment, the voltage value, along with the slope of the voltage curve, can be incorporated in more precisely determining the optimal remaining charge period.

The voltage curves shown in FIGS. 3 and 4 were plotted by measuring the voltage across the cell's terminals when the cell was being charged. However, another possible method is to interrupt the charging current for a short time each time the voltage is measured. This method yields a quite similar curve, but the absolute voltage is slightly lower because the curve does not include the voltage drop caused by the charging current through the internal resistance of the battery. Since this internal resistance generally increases at the end of the charging sequence, this unattended voltage measurement is a more accurate measure of battery condition.

In the above embodiment, the curve slope is measured as follows. The voltage of the battery is measured at each measurement time point, for example, every 1/10 second, and then this voltage value is stored in the memory circuit by the electronic processor. The processor then calculates the difference between this just measured value and the value measured 90 seconds before, for example, and this difference is then used as a measure of the slope of the curve at that time. With this scheme, a new value of the slope is obtained every 10 seconds, for example measured over a period of 90 seconds.

In order that the measured value of the voltage is not affected by a transition phenomenon or the like, the voltage is preferably between the above-mentioned measurement time points.
It is measured many times, for example 100 times. Each of these intermediate measurements is stored in the processor, and then at the actual measurement time, the processor has been taken since the last measurement time.
Calculate the average of 100 intermediate measurements.

When the charging process is aborted as described above, a maintenance charge of the battery is made if the battery is left in the charger. This maintenance charging is done by passing current pulses through the battery at timed intervals. These current pulses and their time intervals are adapted to compensate for battery self-discharge that would otherwise occur. The pulse has a duration of
Between 15 and 30 seconds, the time interval between subsequent pulses is several hours.

FIG. 5 shows a block diagram of an embodiment of the device of the invention.
A voltage of 220V is applied to this device by a conventional plug 1 and that voltage is converted in a block 2 of the rectifier to a DC voltage of 9V. 3 indicates a current regulator, which sends current through terminals 4, 5 to the battery to be charged. The current from the battery returns to the rectifier circuit 2 through the terminal 5 and the ground fault resistor 6. The current regulator 3 is controlled by the processor 7 through the control stage 8. The processor 7 can measure current and voltage by means of an analog / digital converter 9. The charging current is measured by measuring the voltage drop across resistor 6, while the battery voltage is known as the difference between the voltages measured at terminals 4 and 5. The processor 7 is further connected to a memory circuit 10, which circuit i,
It is used to store the current and voltage values measured in a and the calculated stop time. Rectifier circuit 11 is rectifier circuit 2
DC voltage 5V is generated from voltage 9V. This 5V voltage is used to feed circuits 7, 9 and 10. The current rectifier 3 is controlled by pulse width modulation, and the processor 7 controls the pulse width in such a way that the desired charging current always flows through the battery. The processor measures the charging current by measuring the voltage drop across resistor 6 as described above. If desired, the processor can measure the voltage across the terminals of the battery at the time intervals between the current pulses. Therefore, this voltage measurement is not affected by the voltage drop caused by the charging current passing through the internal resistance of the battery.

FIG. 6 is a circuit diagram of an embodiment of the apparatus shown in FIG. The blocks in FIG. 5 are indicated by dashed lines and are given the same reference numbers as shown in FIG. The rectifier block 2 comprises a transformer T1 and a rectifying coupling consisting of four diodes D1, D2, D3 and D4. The output voltage from this block is a DC voltage of 9V, part of which is sent to the current regulator 3 and part of which is sent to the adjustment circuit 11. The current regulator 3 comprises a transistor Q4 and is controlled through the control stage 8 of the processor IC1. This control stage 8 is a resistor R
5, R6, R7 and R8 and transistor Q3. When the output terminal P1.1 of the processor has a high output signal, the transistor Q3 is rendered conductive by the voltage divider having resistors R7 and R8. The current is therefore divided by voltage divider R5 and R6.
Flowing through, these voltage dividers cause Q4 to conduct, resulting in current being delivered to the battery. Processor output terminal P1.1
When the output of is low, the charging current is not sent to the battery because the transistors Q3 and Q3 are in the non-conductive state.

The analog / digital converter 9 includes an integrated circuit IC2, resistors R2 and R3, and smoothing capacitors C4 and C7.
The measured voltage, which represents the battery voltage and the charging current, is converted into digital information in the integrated circuit IC2, which digital information is further sent to the terminals P1.2 and P1.3 of the processor.

In this embodiment, the processor circuit IC1 comprises a processor 7 and a memory circuit 10. More capacitors
C1, C2 and C3 and crystal X1 are connected to the processor. Otherwise, the operating mechanism of this processor circuit is generally conventional.

The regulator circuit 11 includes an integrated voltage regulator IC3 and capacitors C5 and C5.
Equipped with 6. This circuit applies a DC voltage of 5V to the circuit IC1 and IC
Send to 2.

The circuit may control the voltage to maintain the charging current at a substantially constant value, or control the current during charging the battery to maintain a substantially constant voltage, or a combination of these methods. Used to decide what to do.

When charging a rechargeable battery according to the present invention as described herein, the charging process is such that during the "remaining charging period" between the terminals of the battery when the predetermined maximum voltage value Vmax is reached. The voltage measured at is controlled so as to be maintained at a constant value. The Vmax for a particular type of battery can be determined as described above.

However, some batteries never reach the predetermined value Vmax determined for this battery of this type. This is due to various defects or anomalies in these batteries. FIG. 7 shows the charging curve for such an abnormal battery. During the first period of the charging process, the charging curve follows the same normal course as shown in FIG. However, the voltage curve flattens out at a voltage V'lower than Vmax. Therefore, the time to stop the charging process cannot be determined based on the time when the charging voltage reaches Vmax. In such cases, the maximum charging voltage can be determined in another way. For example, the battery voltage is measured at predetermined time intervals and then the measurements are compared. If the measured battery voltage has not risen during the last continuous measurement and Vmax has not yet been reached, the last measured voltage shall be the maximum voltage V'of this battery.
And the remaining charge period is determined starting from the time V ′ is first measured.

FIG. 8 shows a typical first charge curve when test charging a virgin battery and FIG. 9 shows the corresponding charge curve when test charging a fully charged battery. When the battery has to be charged for the first time, or for the first time after being stored for a long time without being charged, the chemical reactions that should occur in the battery during the charging process start much slower . For such batteries, the controlled high current charging process described above cannot be used. In the case of such a "virgin battery", the charging process ensures that the battery is fully charged,
It must be delivered to the battery for a relatively long period of time at a relatively low, almost constant current. Therefore,
Before starting the actual charging process, the battery is charged with the test charging program and then briefly charged by the normal charging process described above. However, the charging current at this start must be relatively low, for example in the range of 1 C / h and then raised to a high value which may be in the range of 4 C / h. Note that C / h is the so-called C-rate. The charging process is stopped after a predetermined short period of time, for example a few seconds, or when the voltage across the battery terminals reaches Vmax. The cell is discharged with a relatively high discharge current. Figure 10
FIG. 9 is a graph showing a discharge curve of a virgin battery charged as shown in FIG. FIG. 11 is a graph showing a discharge curve of a full load battery charged as shown in FIG.

Fig. 8 shows that a virgin battery can, for example,
It shows that the battery voltage Vmax is reached in a shorter time than a second. However, the charging current that the battery accepts is very low. As a result, as shown in FIG. 10, the virgin battery charged according to FIG. 8 is completely discharged in a very short time (less than 1 second in this example). If a curve similar to that of FIGS. 8 and 10 is obtained when the battery is subjected to a test charge, the control system of the charger is instructed to treat the battery as a virgin battery and during the subsequent charging process the battery is A relatively low, almost constant charging current of, for example, about 0.2 C / h is delivered to the battery until the battery is charged to full capacity.

When a full-load battery is test-charged, the voltage across its terminals reaches Vmax within the same period as the virgin battery, as shown in FIG. However, unlike the charging current delivered to the virgin battery, the charging current delivered to the fully loaded battery increases very quickly. During the test, when the fully loaded battery was discharged, an almost constant high current was drawn from the battery during the test period, while the battery voltage was fairly constant as shown in FIG. If a curve similar to that shown in Figures 9 and 11 is obtained when the battery is subjected to a test charge, the charging system is
It is instructed to treat the battery as a fully charged battery (which means the charging process is stopped).

Alternatively, the rate of change of the voltage curve may be measured during the charge test and the discharge test. By comparing the measured rate of change of the voltage curve with a reference value, the starting conditions for the battery can be calculated, so that the charging process can be selected for the battery to be tested. If desired, the test program may be provided with any number of consecutive charge and discharge periods to obtain the desired information.

When choosing the ideal charging process for a battery, it is necessary to have a set of reference parameters for the type of battery being charged. Therefore, it is desirable to have a way to determine or select a set of reference parameters for a new type of battery.

These parameters include battery voltage, charge and discharge currents, battery internal and external temperatures, and / or chemical reactions within the battery cell.

One of the most important parameters is the battery temperature when the battery is fully charged: Temp (100%). If charging is further performed from this point, the temperature of the battery rises and the battery is damaged.

In order to measure the Temp (100%) of an unknown type of battery without being significantly affected by the heat dissipated by the series resistance in the battery, the battery uses a relatively low, almost constant charging current. In order to fully charge the battery, charge it for a relatively long time (several hours). When the battery is charged, it is in fact discharged for a relatively long period of time to test whether it is fully charged. If not fully charged, start a new charging process with a higher charging current. If fully charged, start a new charging process with the same charging current, but in this case reduce the charging time. When this charging process is stopped, the battery is discharged again to determine if it is fully charged.
If fully charged, it begins a new charging process with the same charging current but a shorter charging period.
If not fully charged, initiate a new charging process with the same charging current but a longer charging period. These charging and discharging processes have a minimum charging time: t
Continue with a new charging period using the same charging current until (100%) is found (time when the battery is just fully charged). When the temperature of the battery is measured at t (100%),
Temp for a given charging current for this type of battery
(100%) can be found. By measuring the voltage across the terminals of the battery at t (100%), v (100
%) Value can be found. FIG. 12 shows the course of voltage and temperature values for a typical charging process with a relatively low charging current. In Figure 12, the charging current is 2C
/ h, and points: Temp (100%) and V (100%) are shown on the curve of charging voltage and temperature shown in the figure.

It should be understood that as another method for obtaining the value of Temp (100%), a method of measuring the rate of change of the temperature curve during charging can be used.

Another important parameter used in the present invention is a predetermined maximum voltage that varies with the type of battery involved.
Vmax. When using the fast charging process as shown in FIG. 3, the charging process is controlled as follows. That is, the voltage is maintained at a substantially constant value during the rest of the charging process when Vmax is reached, and the charging process is stopped when a predetermined period of time has elapsed starting from when Vmax was reached. Controlled.

To determine the Vmax for a new type of battery,
The temperature: Temp (100%) is determined by charging with a charging current that is slightly higher than the charging current used in the above example and is almost constant. The rate of change of the voltage curve is measured and compared with the battery temperature. If the rate of change of voltage is positive at Temp (100%), the new charging process is started with a new charging current slightly higher than the previous current. This process is called Temp
Repeated until the rate of voltage change measured at (100%) is zero or slightly negative. This method uses the same battery as shown in FIG. 12 and shows a case where the charging current is 0.5 C / h in FIG. 13 and a case where the charging current is 1 C / h in FIG. The value of V (100%) measured for a charging process where the rate of change of voltage is just zero or slightly negative is chosen because it is a good measure of the value of Vmax for this type of battery. The value of Vmax is V (10
A value close to this measured value of 0%) should be chosen. Other methods can also be used to determine the value of Vmax.

Fig. 15 shows the maximum charging current of 4C / h and V (100
%) Using the maximum charging voltage Vmax determined from the measured value of
FIG. 15 shows the controlled charging process of the present invention performed on the same battery as shown in FIGS. 12-14.

By measuring t (100%), Temp (100%) and V (100%) as described above, a set of reference parameters indicating voltage, temperature, current and charge time reference values can be collected. . All of these reference values can be used to determine the charging characteristic parameters used in the controlled charging process, including other methods of calculating Vmax.

According to another embodiment of the invention, the reference parameters used for the controlled charging process are per battery or per type of battery by using a first analytical charging process and then a second analytical charging process. You can ask. If the battery is made up of several tanks,
These analytical charging processes can also be used to determine the reference parameters for each cell of the battery.

The first analytical charging process is shown in FIG. In this analytical charging process, the maximum battery charge temperature difference ΔT is measured by sending a relatively low and almost constant charge current for a relatively long period of time and then examining the battery temperature and / or the battery terminal voltage. This first analysis charging current must be low so that no substantial increase in battery voltage is detected during the first 6 hours of the charging process. However, this charging current must be high enough to ensure that the battery voltage rises after about 10 hours of charging, and the exact value of the capacity of the battery is the time when the first analytical charging process is performed. As may not be known, the charging current should preferably be about 0.1 C / h. If a value for the first analytical charging current is selected, but the above requirements for the voltage of the battery are not met, then a new value for the first analytical charging current must be selected and then the entire analytical charging process is Start again. The cell is preferably completely discharged prior to any analytical charging process.

If the correct value for the first analytical charging current is selected, the battery will be fully charged after several hours of charging and no further temperature rise of the battery will be detected. Therefore, the maximum charge temperature difference ΔT can be determined for the battery by comparing the minimum and maximum measured battery temperatures. It should also be noted that when the battery is fully charged, no further increase in battery voltage is detected. If a temperature sensor is available for each cell of the battery, then the maximum charge temperature difference can be measured for each cell of the battery.

According to another aspect of the invention, there is provided a method of determining the actual value of the capacity of a battery to be charged. The method is also performed during the first analytical charging process as follows. That is, when no further increase in battery temperature and / or battery voltage is detected for a predetermined period of time that includes at least two measurements of battery temperature and / or voltage, the first charge termination time point. : t (capacity) is measured. Alternatively, t (capacity) can be determined as the point in time when changes in battery temperature and / or battery voltage drop below a predetermined level for a predetermined period. During the first analysis charging process, the actual value of the battery capacity can be determined by calculating the power delivered to the battery up to the time: t (capacity) (equal to the time when the battery is fully charged) .

The second charging process is shown in FIG. During this analytical charging process, the maximum battery voltage across the battery is almost constant at a second analytical current at a second analytical current equal to the C-rate based on the actual capacity value of the battery measured during the first analytical charging process. Measured by sending the analytical charging current. During the second analytical charging process, the voltage across the terminals and the battery temperature are investigated, and when the temperature of the battery rises due to the maximum battery charging temperature difference ΔT measured during the first analytical charging process, the battery temperature rises between the battery terminals. The maximum terminal voltage is determined as the measured value. When examining the inter-terminal voltage for each cell of the battery, the maximum inter-terminal voltage shall be the maximum cell voltage at the maximum battery charging temperature difference, or the maximum cell temperature difference when examining the temperature individually for each cell. The same method can be used for each tank.

18, 19 and 20 show the charging curves of NiCd cells when the charging process is controlled according to the results obtained during the first and second analytical charging processes. Therefore,
The actual battery capacity value measured during the first analytical charging process is available when measuring the charging current delivered to the battery during the first part of the charging process. In Figures 18, 19 and 20, this charging current is equal to twice, three times and four times the C-rate, respectively. During this charging process, the voltage across the battery terminals is investigated, and when the maximum battery terminal voltage Vmax determined during the second analysis charging process is reached, the charging process keeps the voltage constant during the rest of the charging process. Controlled to be done. At the time Tmax when Vmax is reached, the remaining charging period is determined according to the above-mentioned idea, and when this remaining charging period has elapsed, the charging process is stopped.

However, the remaining charging period can be determined by the value of Tmax. And in a preferred embodiment, the remaining charge period is determined by comparing the value of Tmax with a stored reference value that includes the corresponding remaining charge period, and then selecting the remaining charge period that corresponds to the value of Tmax. It is determined.

When charging the battery, the temperature and / or charging current of the battery is investigated and the charging process is stopped when the measured temperature rise equals the maximum battery temperature difference measured during the first analysis charging process. It Alternatively, the charging process is stopped when no further drop in charging current is detected for a predetermined period of time during the remaining charging period. This shows the charging curve of a nickel metal hydride battery initially charged with a very high charging current.
Shown in 21. In this case, Vmax is reached very quickly and the charging process is controlled so that the voltage across the battery terminals is held constant at Vmax, resulting in a decrease in charging current and then a further decrease in charging current. The charging process is aborted when no more is detected.

As mentioned above, a battery has several battery cells. These cells are connected in series, and the resulting battery voltage depends on the number of battery cells in the battery. However, the characteristics of the battery cell are different for each cell within the cell, so to obtain near complete control of the battery discharge and charge process, each individual cell should be treated while it is being discharged and / or charged. It would be convenient to be able to measure the voltage and / or temperature of the cell.
Thus, in an aspect of the invention, there is provided a battery having at least two battery cells and including means for measuring the voltage of each battery cell. The battery of the present invention may further comprise an information means for storing the measured battery cell voltage. And in a preferred embodiment of the battery of the present invention, each battery tank is equipped with a temperature sensor, and the measured temperature is stored in the information means. FIG. 22 shows a block diagram of a preferred embodiment 20 of the battery of the present invention. The battery 20 shown in FIG. 22 includes six battery tanks 21 to 26 each having temperature sensors 27 to 32, and an EEPROM.
And / or information means 33 such as a microprocessor for reading the voltage across each battery cell terminal and / or the temperature of each battery cell.

Since the characteristics vary from cell to cell, it is very important to control the discharge process for the cell with the largest drop in cell voltage during discharge. Figure this
Shown at 23 and 24, these figures show the discharge curves for each cell of a NiCd cell having 6 cells and discharged at constant current. In FIG. 23, the total voltage of the battery is used to stop the discharge of the battery by discharging at a very high level by making the voltage drop in at least one of the batteries relatively large.
As a result, when the battery is subsequently recharged, the battery cell will not be fully charged and the capacity of the battery will decrease. This phenomenon can be avoided by the discharge process shown in FIG.
That is, in this case, the discharging process is controlled so that discharging of the battery is stopped when the first one of the battery cell voltage curves drops to a predetermined level. This level is in the range 0.8-1 volt.

Similarly, the maximum battery cell voltage is not reached at the same time during the charging process. This is shown in FIG. That is, Fig. 25 shows Ni
The battery cell voltage curve of each battery cell during discharge of the Cd battery is shown.
It is observed in FIG. 25 that one of the battery cells reached the maximum battery cell voltage earlier than the other battery cells, and in a preferred embodiment of the present invention, the remaining charging period of the charging process is Must be determined when one of the above voltages first reaches the maximum battery cell voltage.

26, 27 and 28 show block diagrams of various embodiments of the battery system of the present invention. FIG. 26 shows a system in which the battery 40 has an information means 41 such as an EEPROM and the charging device 42 has a control device 43 such as a microprocessor.
However, the information means 41 of the battery 40 may be provided with a control device such as a microprocessor as shown in FIG. Figure 28
Shows an embodiment in which the charging control device is contained in the information means 41 of the battery 40, in which case the battery 40 need only be connected to a power supply 44 controlled by the information means 41 of the battery. .

It should be understood that the above first and / or second analytical charging process is used in connection with the battery of the present invention and the measured data and parameters are measured and / or stored in the information means of the battery. is there. Alternatively, the data can be collected by a computer system that sends the characteristic parameters to a charging device with a memory that stores these parameters.

Also, the method of the present method is not limited to nickel being effective only in one type of battery, such as a cadmium battery, and in other types of rechargeable batteries, such as lithium batteries and nickel metal hydride batteries. It should be understood that it is available.

Front Page Continuation (72) Inventor Raple, John Denmark, Decay-2930 Crampenborg, Fabricas Are 17 (72) Inventor Jules-Hansen, Ebe Denmark, Decay-3660 Stenlese, Gunlesparken 31 Panel Judgment Nagayuki Yukio Judge Junko Yoshimizu Judge Michiko Sakai (56) Reference JP-A-2-294231 (JP, A) JP-A-64-59179 (JP, A) JP-A-3-285522 (JP, A) Kaihei 3-277130 (JP, A) US Pat. No. 4885523 (US, A) European publication 124739 (EP, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/42-10/48 H02J 7/00-7/36

Claims (13)

(57) [Claims] 1. A rechargeable battery (40) having at least one rechargeable battery cell, a pair of battery terminals, and information means (41) for entering information about the battery in the form of an information code; Electronically the information code of the charger terminal, the means for removably connecting the battery and the charging device so that the terminal of the battery makes conductive contact with the terminal of the charger, and the information means of the battery (41). A rechargeable battery having information receiving means for reading or detecting and having control means (43) for controlling the charging process based on the information code read or detected by the information receiving means of the charger ( A charging device (42) for charging the battery (40), wherein the information code is the maximum charging voltage of the battery (40) and / or
Alternatively, the battery charging system includes information about the maximum charging current and information about at least one process for determining or selecting at least one charging parameter. 2. The battery charging system according to claim 1, wherein the information code further includes information regarding a maximum battery temperature. 3. The information code is battery type and / or
Alternatively, the battery charging system according to claim 1 or 2, further comprising information regarding a capacity of the battery. 4. The information means (41) comprises an electronic memory for storing battery information, according to claim 1.
Battery charging system described in 1. 5. The battery charging system according to claim 1, wherein the information means (41) comprises an EEPROM. 6. The control means (43) of the charging device (42),
The battery charging system according to claim 1, further comprising a microprocessor. 7. The battery charging system according to claim 1, wherein the rechargeable battery (40) is a nickel cadmium battery, a nickel metal hydride battery, or a lithium battery. 8. An at least one rechargeable battery tank, a pair of battery terminals and an information means (41) having battery information in the form of an information code, said information code corresponding to a battery charging device (42). ) Has a form that can be electronically read or detected by the information receiving means, the information code determining information about the maximum charging voltage and / or the maximum charging current of the battery and at least one charging parameter. A rechargeable battery further comprising information on at least one process for selecting. 9. The rechargeable battery of claim 8, wherein the information code further includes information about maximum battery temperature. 10. The information code further comprises information regarding battery type and / or battery capacity.
Or the rechargeable battery according to item 9. 11. The rechargeable battery according to claim 8, wherein the information means comprises an electronic memory for storing battery information. 12. The rechargeable battery according to claim 8, wherein the information means comprises an EEPROM. 13. The rechargeable battery according to claim 8, wherein the rechargeable battery (40) is a nickel cadmium battery, a nickel metal hydride battery, or a lithium battery.